<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>

      for(;;){
      let nuser = prompt('输入用户名')
      let password = prompt('输入用户名密码')
        if(nuser === 'admin' && password === '123456'){
          alert('登录成功')
          break
        }else if(nuser !== 'admin'){
          alert('用户名错误，重新输入')
        }else if(password !== '123456'){
          alert('密码错误，重新输入')
      }
    }
    </script>
  </body>
</html>
